In many different application forms, fluid conducting lines, thus fluid lines with other fluid lines or with connections which run to a fluid source or a fluid sink, have to be connected in a communicating manner. For this, various connecting techniques, in particular coupling units, are known. In certain applications, little installation space is available for establishing or detaching such a connection. Furthermore, for a series production it can be desired to keep the assembly of the connection as simple as possible. In particular for motor vehicles it can be required to connect gas-conducting lines in an engine compartment with other gas-conducting lines or with adequate connections.